///
/// ♪ Let the voice of love take you higher! ♪
///
#include <bits/stdc++.h>
#define Loop(x,l,r) for(ll x = ll(l); x < ll(r); ++x)
#define F first
#define S second
typedef long long ll;
typedef std::pair<ll,ll> pll;
using namespace std;
ll inf = 1e9+100;
const int N = 100010;
pll a[N];
int k, n;
ll get(int l, int r, int x)
{
ll ans = 0;
Loop(i,l,r)
ans += abs(a[i].F-x)+abs(a[i].S-x);
return ans;
}
ll bin1(int L, int R)
{
ll l = 0, r = inf;
while(l < r)
{
ll m = (l+r)/2;
ll v1 = get(L,R,m);
ll v2 = get(L,R,m+1);
if(v1 < v2) r = m;
else l = m+1;
}
return get(L,R,l);
}
ll bin2()
{
ll ans = 1e18;
Loop(i,0,n+1) ans = min(ans, bin1(0,i)+bin1(i,n));
int l = 0, r = n;
while(l < r)
{
int m = (l+r)/2;
ll v1 = bin1(0,m)+bin1(m,n);
ll v2 = bin1(0,m+1)+bin1(m+1,n);
if(v1 < v2) r = m;
else l = m+1;
}
ll ans2 = bin1(0,l)+bin1(l,n);
assert(ans2 == ans);
return ans;
}
int main()
{
ios::sync_with_stdio(false); cin.tie(0);
#ifndef EVAL
freopen("in.txt", "r", stdin);
#endif
cin >> k >> n;
ll stoneocean = 0;
Loop(i,0,n)
{
char c1,c2; ll a1,a2;
cin >> c1 >> a1;
cin >> c2 >> a2;
if(c1==c2)
{
stoneocean += abs(a1-a2);
--i; --n;
}
else
{
a[i] = {a1,a2};
stoneocean += 1;
}
}
sort(a,a+n,[](pll& x, pll& y){return x.F+x.S < y.F+y.S;});
cout << stoneocean+(k==2?bin2():bin1(0,n)) << '\n';
}
